Electric system to control impedances



Sept.f7, 1948. v F. J. HOOVEN 2,443,335

ELECTRIC SYSTEM TO CONTROL IMPEDENCES Filed Sept. 29, 1945 INVENTOR.

W 6674M. W WMQM ATTORNEYS Patented Sept. 7, 1948 UNITED STATES PATENT OFFICE ELECTRIC SYSTEM TO CONTROL IMPEDANCES Frederick J. Hooven, Dayton, Ohio Application September 29, 1945, Serial No. 619,336

Claims. 1

This invention relates to electrical circuits and more particularly to electrical systems.

It is the principal object to provide an electrical switching system for rapid and accurate control of a group of impedances from a single control member to vary the impedance progressively over a wide range in uniform increments.

It is also an object to provide control means for groups of impedances arranged in a units or first order group, and at least one higher order group in which the entire range of values may be traversed progressively in uniform increments, avoiding any open circuit positions or abrupt changes in the circuit values.

It is a further object to provide a system having circuits arranged in groups of a first and at least one higher order of values with switch means for each group coupled together and operable from a single shaft in which the total value of the groups included in the circuit is a func tion of the total angle to which such shaft is attached, the system providing for traversing the entire range of values in a continuous man.- ner and with no greater change of values at any time than approximately that of the first order of values.

It is also: an object to provide an electrical switching system having circuits of a first and at least one higher order of values'which are arranged to be switched progressively in steps of the first order of values'over the entire range without causing any change in values as great as the second or any higher order of values.

' Other objects and advantages will-be apparent from the following description, the accompanyi-ng drawing, and the appended claims.

In the drawing, the single figureis a schematic view showing the single control element and the group of switching arms operatively related thereto, in accordance with the present invention.

The provision of decade type switches is well known in which electrical cir-cuits,such for example as resistors, reactors, or other impedance's, are arranged to be adjustable'and progressively included in an electrical circuit. For example impedances may be arranged in a group of a first order of values, and in other groups of a second, third, or still higher order of values. Thus, as a specific example, the first order group may comprise 10 resistors each having a resistance of 1 ohm, the second order group comprising ten resistors each having a resistance of 10 ohms, the third order group comprising ten resistors eachv having a resistance of 100 ohms, and

so on. By providing separate switch arms for the resistors of each group, a total resistance may be selected to have any (integeiuvalue between 1 and 1,000 ohms.

Further analysis will show that if the adjustable contact arm of the first order group of resistances is wide enough to span two adjacent contacts, it will not cause open circuits at any time and the maximum change inthe total resistance in the circuit at any time will be only the value of a unit of the first order group, in the case above referred to, such value being 1 ohm. However when the contact arm of the second order leaves one resistance point and passes to the next adjacent point, it will cause an abrupt change in the resistance in the circuit of a unit f the second order of values, namely, 10 ohms in the case assumed. Similarly the changes occurring upon movement of the third order switch arm will be abrupt changes or steps or ohms each. With such an arrangement a sharp change in the electrical values in, a circuit will thus occur at each transfer of the switch arms of the second and any higher order of values, interfering with the smooth and regular progression which is desired for many purposes. Similar analysis will show that if the switch arms are of less width so that they do not span adjacent contacts, open circuit conditions will occur in addition to the abrupt changes in values described, and additional objectionable line conditions will thus be involved.

The present invention provides a switching system of the sci-called decade type in which resistors, reactances or other electrical circuits are arranged in a first order group and at least one higher order group. A single continuously adjustable control element is provided in conjrunction with suitable switching means So that by continuous operation of the control member, the entire range of values may be progressively traversed with regular and uniform steps, the increments being those corresponding to the first order of values. This uniformity continues through the operation of the switching elements for the control of the second and higher order of values, there being no abrupt change in the circuit values at the time when the switch contacts establish or break connection with the circuits of the :second or any higher order of values.

Referring specifically to the example above given, the present invention provides for including resistance in a circuit beginning with 0 ohm up through 10 ohms in the first order of values, then upon further operation of the control memthe same mannerthrough the entire range of the circuits provided. At no time is the circuit left in an open condition and there are no abrupt changes in the resistance included in the circuit, the steps being regular and uniform and by 1 ohm values throughout the entire range. Further the actual resistance in the-circuit, any time is a direct function of the'total an'gle through which the control member has been up.

erated so that a highly desirable system ,is prov vided which is particularly suited by automatic or remote control.

Referring to the drawing which discloses a preferred embodiment of the invention, the electrical circuits are represented by way 'of illustration as resistances. They were arranged in groups comprising a first order group made-up'of resistors Rl to RIO respectively. While-the system herein shown makes use of ten resistors in each group, and is thus based on a decimal system, it will be evident thatthe number of units in each group may be selected as desired and may be either less or greater-than the ten :whichhave been illustrated. For example, an advantageous arrangement is comprised of 12 units in each group'andw'ould thus be based on a duodecimai system. In *anycase the values of each one of theimpedances of the second order group are the same as the value of entire bank of first order impedances.

The resistors of the second order groupare shown at RSI through R40, and each has ten times the resistance of those of the first order group. The resistors of the third-order group are shown at RU through R", each of which comprises times theresistance of the units of the second order group or a resistance of. 100 times that of the resistors of the "first order oup- "Resistors Rl to R1] are connected in series relation with each other and connections are brought out from each resistor to a series of contact terminals correspondingly numbered I through It which are mounted concentrically on a suitable insulating plate l2; A movable switch arm I4 is mounted on shaft l5 for movement in a continuous manner over the contacts to- I0. As'shown it is of sufficient width so thatit will span two adjacent contacts.

Shaft I5 is shown as beingrotated by a handle for manual operation, it being understood that any desired automatic operation or control may be "utilized instead of the manual control. A cam llis mounted on shaft It, the cam having high" and low areas which are approximately Equal-in their arcuate extent.

"Cam I! controls a single polev double throw toggle or snap action switch comprising amovable contact arm 24 which is actuated by the cam between two positions where it closes alternately with contacts 2| and 22. The cam is so arranged relative to switch arm that when rotated in the direction indicated by the arin the drawing, thehigh portion of the cam engages with spring arm 2|lto cause the opening of switch contact 22 and the simultaheous closing of 2| at the time when 4 the switch arm H of the switch is centered over contact terminal l0.

Resistors R3| to R40 comprising the group of values of the second order, are also connected in series relation with each other and connections are made from the several resistors to contact terminals numbered 3| to 40 which are concentrically mounted oninsulating plate 42. In addition a second insulating plate 48 is provided which is mounted in parallel but axially spaced relation with plate 42 and which also contains a series of contacts connected with the same resistors 3| to 40 and marked ll through 40' respectively.

:A main movable switch arm 44 is mounted on shaft 45 for movement over contacts 3| to 40 and like arm I4, is of suflicient width to span each twq adjacent contacts. Shaft 45 also carries another switch arm 46 which traverses conall) tacts 3 I to 40'. Auxiliary switch arm 46 operates in imison with arm 44, but as shown is angularly displaced therefrom or retarded by one step or contact. Thus when arm 44 is on contact 45, for example,- arm 46 is on contact 34. Further, arm 46 is-not wide enough to span adjacent contacts, but is of such width that upon movement in either direction it establishes contact withthe terminal toward which it is moving before arm-44- breaks contact with the terminal it is leaving.

Shaft 45 is driven by alarge gear 50 engagingwith's'mall pinion 5| of shaft l5. The ratio is such that a complete revolution of shaft It causes the advance of shaft 45 and of the contacts 44 and 46 by one step. Shaft 45 carries a cam 51 similar to cam which actuates the movable switch arm 60, forming part of a snap action switch similar to switch 20, to cause it to close alternately with its contacts 6| and 62.

Resistors RH through R80, comprising the circuits of the third, and in this case the highest. order of values, are similarly connected in series relation with each other. A double set of insulating plates 82 and 83 are each arranged with its respective-sets of contact terminals II to and II to 80', similar to the arrangement of the resiStors-of the second order of values described above. Main and auxiliary switch arms 14 and It cooperate with contacts II to 80 and 1| to 8|! respectively, arm 16 being displaced or retarded by one step relative to arm "as above described with respect to arms 46 and 44. Both switch arms are rotated in unison by shaft 85 from gear 40 driven by pinion 9| on shaft 45. Again the reduced ratio is such that shaft 85 and its contact arms I4, 16, are advanced by one step in response to aoomplete rotation of shaft 45.

Switch arm 20 is directly connected with res tor R1 byline 95, while contact 2| is connected with terminal ID on the first'bank of resistors by line 96. Contact 22 is connected directly to the auxiliary switch arm 46 of the second bank of resistors byline 91.- One side of the main circuit is indicated at I04, connection from which is made directly to the resistor R", and a parallel connection being made to themovable switch arm |4. Resistor BI is also connected directly to R44 as shown at I02 and by a. parallel connection I to. the movable switch arm 44. Resistor 3| is connected-as shown at llfl to switch arm 60, and through line ||2'with the first unit RII of the third bank of resistors, a parallel connection 4 also being: made to the switch arm 14. Contact 6| is connected-to terminals 40 and 40' while contact Otis connected to the auxiliary switch arm 5 16' of the third bank of resistors Connection is made by aline H5 fromthe end of resistor RBI] to th opposite main line terminal IIIj.

In operation, the system above described functi-ons in the following manner. Assuming a rotation of shaft I5 in the direction of the arrow shown'in the drawings, i. e., counter-clockwise, movable-contact I4 moves over the terminals I to II) in sequence, providing for gradually increasing th resistance in the circuit in uniform steps-of the value of each individual resistance element. The circuit through the first bank of resistors may be 7 followed from terminal II'III, through the rotatable switch arm I4, to the contact terminal-which it engages, into the successive resistors Rn down to RI which may be included, and out through line I02 to the resistors of the second and third banks which may be included. Thus with control in the position shown, the circuit may be traced through line I 03, switch arm 44, resistors R35, R34, R33, R32 and R3I line III), line II2, line II4, switch arm I4, resistors R18 through RH, and from line H5 to the opposite circuit terminal I I6.

As the arm l4 moves from terminal I to terminal 5 the high portion of the cam II maintains switch arm 20 against contact 2I thus completing a circuit from terminal III directly to the outer terminal of RI. Since however terminal I is not connected with the bank of resistors in any way, this circuit is ineffective under these conditions.

As the switch arm I4 moves from terminal to terminal 6, the low point of cam I'I engages the switch arm 20 and allows the same to move under its spring action, opening contact 2I and closing against contact 22. This establishes a circuit from line I05 to the movable switch arm 46 which is trailing behind contact 44, but moving toward the same contact point which arm 44 is leaving. Thus by way of example when switch arm 44 leaves contact 34 and approaches contact 35, arm 46 approaches its contact 34', and establishes contact therewith before switch arm 44leaves its contact 34. It will thus be evident that during the remaining half of the revolution of shaft I5, and even following the complete opening of the circuit between switch arm 44 and its contact 34, the line circuit is maintained through line 95, switch 20, contact 22, line 91, and auxiliary switch arm 46, which is in direct contact with its contact 34'. Thus there is no premature incorpora- .tion of the next step of resistance in the circuit, until that condition is desired, and the fact that main switch arm 44 has moved up to contact 35 is inefiectual.

As the final movement of switch arm I4 into contact with its terminal I0 is completed, it will be evident that the final unit value of the resistance has been included in the first bank of resistors, corresponding for example to four units in the second bank comprising resistors R3I to R34 and units in the first bank comprising resistors RI to RIO. At this point, the rise of cam I'I engages switch arm 20, causing it to move rapidly from its closing position against contact 22 to its closing position against contact 2I This movement effects the opening of the circuit through auxiliary switch arm 46 which is on contact terminal 34', and the circuit is then completed through main switch arm 44 which engages contact 35, thus including the next unit or resistor R35, in the circuit. Simultaneously, the closing of switch arm 20 against contact 2I establishes a short circuit for the entire first bank of resistors RI to RIIl so that the total resistance in the circuit remains the same. There is therefore no abrupt change in the total resistance-included in the circuit, the switching operation above described providing for the simultaneous incorporation of an additional step of resistance of the second order of values concurrently with the exclusion of the entire firstorder group of resistances.

It will be evident from the above that further operation of shaft I5 provides for reincorporation of the first bank of resistors in a step by step manner, with similar switching of the circuits of the final or last step of the units resistances, in the manner described above. It will also be clear that the system works equally well in both directions, providing for selective increase or decrease of the resistance values in the uniform steps, in the manner already described.

The functioning of the third order group of resistances is similar to the operation-already described, the lower value circuit being established through switch arm 16 while switch arm 14 completes its movement to the next succeeding position, with the final transfer of the circuits being governed by cam 51 to occur upon the movement of switch arm 44 to terminal 40. It'will thus be clear that the inclusion or exclusion of one of the resistors R'II or R80, comprising resistors of thethird order of values, efiects no change in the overall value of the resistance in the circuit, and again there is no abrupt change in the circuit, the maximum change which occurs being approximately that corresponding to a single unit of the first order of values.

It will also be clear that the final position of all of the contact arms described above, as well as the total value of resistance (or other electrical values) included in the circuit will be a direct function of the total angle through which shaft I5 has been rotated. It is thus possible to provide for automatic control of a group of electric circuits over a wide range of values while assuring uniform and predetermined electrical circuit conditions at all times, the total value of which is a direct function of the total angle through which the control shaft has been operated. The device is extremely simple and both reliable and satisfactory in operation, providing for the obtaining of new and highly advantageous results in switching systems of the character described.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise'forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A continuously variable system comprising a group of electrical circuits of a first order of values, at least one additional group of electrical circuits of the next higher order of values, a continuously adjustable control shaft, a first control member operable by said control shaft through a cycle of movement to progressively connect with all of the circuits of said first order of values, a second control member for connecting with said circuits of the higher order of values, means for opera-ting said second control member in coordinated relation with said first control member, switch means actuated respectively by said control members for progressively connecting with said electrical circuits of both said first and said higher order of values in uniform incre- 7 Instant greater those 01 said first arder ervsines and means establishing a continuously. clued oircmtthroogh said switch means includhim-electrical circuits of both said first order d mind 01" said higher'o'rder of values.

2: A continuously variable system" comprising sigromp-orelectmaicircuits o'i' a first order of volts, at least one additional group oi. electrical circuits of the next higher order of values, a continuously adjustable control shaft, a first control member operatic byslid' control shaft through amino! movement toprogressively connect-with all of the eircuttsoi said first order of values, descend-control member iorconnecting with said dl'osdts of the higher order of values, means for operating said-second control member in coordin'sled reiationwith said-first control-member proriding for an advance or one step upon a complete cycle of movement of said control shaft, switdi means actuated respectively by said contact members for progressively connecting with said electrical circuits-of both said first -'and"said ma order of values-in uniform increments not greaterthan those oi" said first order of values, snd means establishing a continuously closed circult Enough said switch means including said ehctrical cirouits-ofboth said first order of values aud o! saidhis'her order'of values. 7

'8. A decade type switching system operable Mm a single continuously adjustable control shaft comprising groups of electrical circuits of [first and at least one higher order of values, a control member continuously adjustable with inspect to first order of values, means coupled with control member and operating in a; reduced speed ratio therewith for connecting with said electrical circuits of said higher order oi 'va'ioes, switch means operated respectively by said controimembers for switching said circuits inpredetermined sequence to selectively traverse the entire range oi. values in uniform steps correspondingto-those oi the first order of values, and meansestabiishing a continuously closedcirouit' through-said switch means including said deeirical oircuitsci' both said first orderoi' values add ct said higher order of values.

I. A-oontlm1ousiy variable switching system house with groupsoi impedances oi. a first and a last one higher order of values comprising switch means progressively adjustable with reto the impedances of said first order of values, a second: switch means progressively allowable with respect: in the impedances of saidliighor' omen oi values, a third switch means slu -progressively adjustable with respect-to the inmedanoes-oflsaidhigherorder of values, means hr: operating: said second and third switch means in correlated relation with said first switch means to provide for a. step -of progression tromone impedance to the next in said second orderupon complete traverse of the impedances oi said first order by said firstswitch means, means for operating said third switch means in olset relation by one step with respect to said second switch means, and auxiliary switch switch means operable at an intermediate point in the cycle of said first switch means for alternately establishing circuits through saidsecond and third switch means to maintain a continuomly closed circuitin which the, impedance ohanges unii'ormly throughout the entire range in increments or said first order otvalues.

5. A continuously variable switching system comprising a group of electrical circuits of a first orderoivalueaat least one additional group oi eiectrical'rcircuitsoi: the mexthigher order 8 values, a: continuously adjustable control sin. a first controlmember operable by said central shaft through a cycle of movement to progressively connect with all of the circuits of first order of values, a second control mambr for the circuits of said higher order 01' V; means for advancing said second control M her by onestep-in responsie to-completion-ot a cycle of movement oi said first control'member. and means for-establishing a'ciroult' through saidsucceeding unit; and simultaneously excluding said first group of circuits upon completions!- said cycle of said first control member;

6. A continuously variable switching systelr comprising a groupof electrical circuits 01- I first order of values, at'least-one additional group of electrical circuits of the nexthigher ordm orvalues, a continuously adjustable control M a first control member operable by said central shaft through a cycle of movement to primessively connect with allot the circuits of said am order of values, a second control member In the circuits of said higher order of values. mans for advancing said second control member by one step in response to completion of a cycle of movement of said first control member. meals to maintain a circuit through a preceding-unit of said second group while said second control member is moving into contact with the sum ceeding unit of saidgroup, and means for estab llshlng a circuit through said succeeding unit and simultaneously excluding saidfirst group of circuits upon completion oi'said cycle or said-firs control member.

7. A continuously variable switching system comprising a group of electrical circuits of a first order of values, at least one additional group of electrical circuits of thenext higher order of values, a continuously adjustable control shaft, a first control member operable by said control shaft through a cycle of movement to progressively connect with all of the circuits of'said am order of values, a second control member for the circuits of said higher order ofvalues, means for advancing said secondcontrol member by one step in response to completion of acycle of move-- ment of said first control-member, meanscsllll lishing amain circuit through the next succeeding unit of said second order group in the direr tion of travel of said second control member, means concurrently establishing an auxiliary circuit through the precedingunit of said second order group, and means for switching fiOIiiOIIQ of said'circuitsto the other at a predetermined point in the cycle 01' said first control member, means establishing a main circuit through'the next succeeding unit of said second'order group in the direction of travel oi. saidsecon'd control member, means concurrently establishing an auxiliary circuit through the preceding unit oi. saidsecond order group, and'means for switching from one of said circuits-to the other at: predetermined polntin the cycle of said first con trol member.

8. A continuously variable switching spam comprising agroup' of electrical circuits of a first order of values, at least one additional group OI electrical circuits of the next higher order or values, a continuously adjustable control shaft, afirst control'member operable by said contl'd shaft through a cycle or movement to M0818- sively connect with all of-the circuits of said firs; order of values, a-second control'member iorti'ib circuitsoi said higher-orderoi values-means!!! advancing said second control member by one step in response to completion of a cycle of movement of said first control member, means establishing a main circuit through the next succeeding unit of said second order group in the direction of travel of said second control member, means concurrently establishing an auxiliary circuit through the preceding unit of said second order group, and means operable simultaneously with completion of a cycle of said first control member for excluding said first order group and transferring from said auxiliary to said main circuit.

9. A switching system operable from a single continuously adjustable control shaft comprising groups of electrical circuits of a first and at least one higher order of values, a first control member continuously adjustable with respect to said first order of values over a cycle of movement successively including the units of said first order group, a second control member coupled with said first control member for connecting with said circuits of said higher order of values and advancing by one step for a complete cycle of said first control member, and switch means for progressively connecting with said circuits in uniform steps of said first order of values including a main contact arm operated relative to said higher order group by said second control member, an auxiliary contact arm also operated by said second control member and offset from said main contact arm by one step, means establishing a main circuit through said main contact arm before said main contact arm leaves a contact, means establishing an auxiliary circuit through said auxiliary contact arm and said same circuit before that circuit has been left by said main contact arm, and means for transferring between said auxiliary circuit and said main circuit.

10. A switching system operable from a single continuously adjustable control shaft comprising groups of electrical circuits of a first and at least one higher order of values, a first control member continuously adjustable with respect to said first order of values over a cycle of movement successively including the units of said first order group, a second control member coupled with said first control member for connection with said circuits of said higher order of values and advancing by one step for a complete cycle of said first control member, and switch means for progressively connecting with said circuits in uniform steps of said first order of values including a main contact arm operated relative to said higher order group by said second control member, an auxiliary contact arm also operated by said second control member and offset from said main contact arm by one step, means establishing a main circuit through said main contact arm before said main contact arm leaves a contact, means establishing an auxiliary circuit through said auxiliary contact arm and said same circuit before that circuit has been left by said main contact arm, means for transferring between said auxiliary circuit and said main circuit, and means for excluding the circuits of said first order group simultaneously with a transfer from said auxiliary circuit to said main circuit.

FREDERICK J. HOOVEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,800,019 Hewett Apr. '7, 1931 2,280,775 Mirk Apr. 28, 1942 Certificate of Correction Patent No. 2,448,885. September 7, 1948.

FREDERICK J. HOOVEN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 14, after the Word order insert group; line 20, for or steps or read or steps of; line 30, after values insert above; column 3, line 24, for were read are; column 5, line 26, after the numeral 5 insert a comma; column 7, line 2, after values insert a comma; column 8, line 9, for responsie read response; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of November, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

